Water Soluble Polymers for Pharmaceutical Applications

Tuning thermal properties of cross-linked DCPD polymers by functionalization, initiator type and curing methods

ROMP derived poly-dicyclopentadiene (poly-DCPD) is a relatively new engineering material with high impact resistance, high chemical corrosion resistance and high deflection temperature.

Lidocaine loaded gelatin/gelatinized tapioca starch films for buccal delivery and the irritancy evaluation using chick chorioallantoic membrane

The aim of this study was to confirm the feasibility of gelatin/gelatinized tapioca starch (α st) films for buccal delivery and to evaluate their irritancy. Lidocaine (LB) and lidocaine hydrochloride (LH) were used as model drugs and glycerin was used as the plasticizer. The scanning electron microscopy, atomic force electron microscopy, X-ray diffraction and thermogravimetric analysis results confirmed the compatibility of gelatin/α st/glycerin (Gαgly) films. Drug releases of LB- or LH-Gαgly films were evaluated. The drug release profiles of medicated films presented good patterns in both short time and 8 h drug release studies. The permeation study was examined through chick chorioallantoic membrane (CAM) by using modified Franz diffusion cells. Moreover, the irritancy study for buccal films was also examined by a hen's egg test on CAM model (HET-CAM). The results revealed that LB and LH could permeate through CAM, and these Gαgly films created no irritation on HET-CAM. This indicates that the LB- and LH-Gαgly films are possible to use as buccal films.

Fabricating Fibers of a Porous-Polystyrene Shell and Particle-Loaded Core

Polystyrene (PS) polymers have broad applications in protective packaging for food shipping, containers, lids, bottles, trays, tumblers, disposable cutlery and the making of models. Currently, most PS products, such as foams, are not accepted for recycling due to a low density in the porous structure. This poses a challenge for logistics as well as creating a lack of incentive to invest in high-value products. This study, however, demonstrated the use of a dry-jet wet-spinning technique to manufacture continuous PS fibers enabled by an in-house designed and developed spinning apparatus. The manufactured fibers showed porosity in the shell and the capability to load particles in their core, a structure with high potential use in environmentally relevant applications such as water treatment or CO2 collections. A two-phase liquid-state microstructure was first achieved via a co-axial spinneret. Following coagulation procedures and heat treatment, phase-separation-based selective dissolution successfully generated the porous-shell/particle-core fibers. The pore size and density were controlled by the porogen (i.e., PEG) concentrations and examined using scanning electron microscopy (SEM). Fiber formation dynamics were studied via rheology tests and gelation measurements. The shell components were characterized by tensile tests, thermogravimetric analysis, and differential scanning calorimetry for mechanical durability and thermal stability analyses.

Aggregated Solution Morphology of Poly(acrylic acid)-Poly(styrene) Block Copolymers Improves Drug Supersaturation Maintenance and Caco-2 Cell Membrane Permeation

Amorphous solid dispersions of polymers and drugs have been shown to improve supersaturation maintenance of poorly water-soluble drugs. Herein, amorphous spray-dried dispersions (SDDs) of poly(acrylic acid)-polystyrene (PS-b-PAA) diblock copolymers with differing degrees of polymerization were prepared in aggregated and nonaggregated states with the Biopharmaceutical Classification System Class II drug, probucol (PBC). Specifically, PS₉₀-b-PAA₁₅, PS₉₀-b-PAA₈₀, PS₃₈-b-PAA₂₂₀, and PS₃₈-b-PAA₃₂₀ amphiphilic block polymers that covered a compositional range in the area of oral drug delivery were prepared to examine the role of molecular weight and controlled aggregation in promoting drug supersaturation and maintenance. In addition, hydrophilic homopolymers PAA₂₀, PAA₉₆, PAA₂₂₆, and PAA₃₉₂ were prepared as controls to evaluate the role of the block copolymer-based SDDs in PBC solubilization. Characterization such as powder X-ray diffraction, scanning electron microscopy, and dissolution tests under nonsink conditions were then performed to evaluate the SDDs. When comparing the block copolymer systems, polymers that were preaggregated into micellular structures prior to spray drying with the drug promoted higher drug solubility and maintenance than when the drug was formulated with molecularly dissolved PS-PAA block polymer. Interestingly, the aggregated PS₉₀-b-PAA₈₀ SDD with 25 wt % PBC achieved 100% burst release and maintained full supersaturation of PBC at pH 6.5 (physiological pH in the small intestine). Dissolution studies conducted at the pH of the stomach (pH = 1.2) show that a minimal amount of drug (∼10 μg/mL) was released, which could be used for protecting drugs from acidic environments (stomach) before reaching the small intestine. To evaluate drug bioavailability, in vitro Caco-2 cell assays were performed, which reveal that PAA-based excipients do not hinder drug permeation across the epithelial membrane and that PS₉₀-b-PAA₈₀ SDD with 25 wt % PBC achieved the highest membrane permeability coefficient. This work demonstrates that block copolymer-based SDDs capable of preaggregating into nanostructures may be a tunable drug-delivery platform that can improve solubility and supersaturation maintenance of Class II pharmaceutics while also not prohibiting bioavailability through model intestinal membranes. Indeed, this concept may be extended to accommodate a myriad of pharmaceutical and excipient structures.

System of Sensors and Actuators for the Production of Water Used in the Manufacture of Medicines

This paper presents the development and implementation of a centralized industrial network for an automatic purified water production system used in the pharmaceutical industry. This implementation is part of a project to adapt an industrial plant to cope with advances in industrial technology to achieve the level of Industry 4.0. The adequacy of the instruments and the interconnection of the controllers made it possible to monitor the process steps by transforming a manual plant, with discontinuous production into an automated plant, improving the efficiency and quality of the produced water. The development of a supervisory system provides the operator with a panoramic view of the process, informing in real-time the behavior of the variables in the process steps, as well as storing data, event history and alarms. This system also prevented the collection of erroneous or manipulated data, making the process more transparent and reliable. Accordingly, we have been able to tailor this water treatment plant to operate within the minimum requirements required by the regulator.

Scalable Production of Monodisperse Functional Microspheres by Multilayer Parallelization of High Aspect Ratio Microfluidic Channels

Droplet microfluidics enables the generation of highly uniform emulsions with excellent stability, precise control over droplet volume, and morphology, which offer superior platforms over conventional technologies for material synthesis and biological assays. However, it remains a challenge to scale up the production of the microfluidic devices due to their complicated geometry and long-term reliability. In this study, we present a high-throughput droplet generator by parallelization of high aspect ratio rectangular structures, which enables facile and scalable generation of uniform droplets without the need to precisely control external flow conditions. A multilayer device is formed by stacking layer-by-layer of the polydimethylsiloxane (PDMS) replica patterned with parallelized generators. By feeding the sample fluid into the device immersed in the carrying fluid, we used the multilayer device with 1200 parallelized generators to generate monodisperse droplets (~45 μm in diameter with a coefficient of variation <3%) at a frequency of 25 kHz. We demonstrate this approach is versatile for a wide range of materials by synthesis of polyacrylamide hydrogel and Poly (l-lactide-co-glycolide) (PLGA) through water-in-oil (W/O) and oil-in-water (O/W) emulsion templates, respectively. The combined scalability and robustness of such droplet emulsion technology is promising for production of monodisperse functional materials for large-scale applications.

Vitreous Wiping, a new technique for removal of vitreous cortex remnants during vitrectomy

PURPOSE

Unremoved vitreoschisis-induced vitreous cortex remnants (VCR) are associated with macular pathology. When present on the retinal periphery, they may play a role in proliferative vitreoretinopathy and retinal detachment after vitrectomy. Existing instruments for their removal involve substantial risk of iatrogenic retinal damage. Purpose of this study was to evaluate the use of a new technique, Vitreous Wiping, for removal of VCR during vitrectomy.

METHODS

Proof-of-concept case series of six eyes (six patients) treated with vitrectomy for various pathologies (macula-on and macula-off retinal detachment, macular hole, macular pucker and vitreous floaters). Vitreous cortex remnants on the surface of the retina were visualized with triamcinolone and removed by Vitreous Wiping with a rectangular piece of polyvinyl alcohol (PVA) held with intra-ocular forceps. Visual acuity and clinical course were assessed during a follow-up of 6 months. All eyes underwent postoperative macular optical coherence tomography. Eyes without preoperative macular pathology, underwent retinal sensitivity testing and eyes without paracentral pathology underwent visual field analysis.

RESULTS

Vitreous cortex remnants could be removed completely in all eyes. There were no intra- or postoperative complications. We observed that PVA is soft like a sponge and vitreous sticks to it, making Vitreous Wiping easier and safer, compared to alternative instruments. Visual acuity improved in all eyes. Microperimetry and visual field analysis revealed no abnormalities related to Vitreous Wiping.

CONCLUSION

Vitreoschisis-induced VCR can be removed effectively and safely from the retinal surface by Vitreous Wiping. Larger studies are needed to confirm this promising finding and its potential impact.

Ionic Polymethacrylate Based Delivery Systems: Effect of Carrier Topology and Drug Loading

The presented drug delivery polymeric systems (DDS), i.e., conjugates and self-assemblies, based on grafted and star-shaped polymethacrylates have been studied for the last few years in our group. This minireview is focused on the relationship of polymer structure to drug conjugation/entrapment efficiency and release capability. Both graft and linear polymers containing trimethylammonium groups showed the ability to release the pharmaceutical anions by ionic exchange, but in aqueous solution they were also self-assembled into nanoparticles with encapsulated nonionic drugs. Star-shaped polymers functionalized with ionizable amine/carboxylic groups were investigated for drug conjugation via ketimine/amide linkers. However, only the conjugates of polybases were water-soluble, giving opportunity for release studies, whereas the self-assembling polyacidic stars were encapsulated with the model drugs. Depending on the type of drug loading in the polymer matrix, their release rates were ordered as follows: Physical ≥ ionic > covalent. The studies indicated that the well-defined ionic polymethacrylates, including poly(ionic liquid)s, are advantageous for designing macromolecular carriers due to the variety of structural parameters, which are efficient for tuning of drug loading and release behavior in respect to the specific drug interactions.

Synthesis and Preliminary Biological Evaluation of 177Lu-Labeled Polyhydroxamic Acid Microparticles Toward Therapy of Hepatocellular Carcinoma

Background: Transarterial radioembolization (TARE) represents an effective targeted therapeutic option for hepatocellular carcinoma (HCC), a cancer with high mortality and poor prognosis. The aim of this study was the preparation and preliminary biological evaluation of ¹⁷⁷Lu-labeled polyhydroxamic acid (PHA) microparticles toward possible use in the therapy of HCC. Materials and Methods: PHA microparticles were synthesized starting from polyacrylamide. They were characterized by Fourier-transform infrared spectroscopy (FT-IR), visual color test, and laser diffraction particle size analysis. Experimental variables such as reaction pH, amount of PHA microparticles, carrier Lu content, and incubation time were optimized for maximum uptake of ¹⁷⁷Lu on PHA microparticles. Stability of ¹⁷⁷Lu-PHA microparticles was tested in the presence of competing Fe(III) ions in solution. In vitro stability of ¹⁷⁷Lu-PHA microparticles was evaluated in 0.05 M sodium phosphate solution (pH 7.5), saline, and serum. Bioevaluation studies were performed in normal Wistar rats by intrahepatic artery injection of the ¹⁷⁷Lu-PHA microparticles. Results: Successful synthesis of PHA microparticles could be confirmed from the results of FT-IR analysis and visual color test. Laser diffraction-based particle size analysis confirmed median particle size to be 54 μm, suitable for TARE. Under the optimized conditions, >99% loading of ¹⁷⁷Lu on PHA microparticles could be achieved. Even in the presence of high concentration of Fe(III) ions, ¹⁷⁷Lu binding to PHA microparticles was stable. ¹⁷⁷Lu-PHA microparticles exhibited excellent in vitro stability in sodium phosphate solution, saline, and serum up to 5 d at 37°C. In the bioevaluation studies performed in normal Wistar rats, 92.8% ± 3.1% of ¹⁷⁷Lu-PHA microparticles were retained in the liver at 96 h postinjection without any significant leakage to other organs. Conclusion: This preliminary study demonstrates the potential of synthesized PHA microparticles as carriers of therapeutic radioisotopes such as ¹⁷⁷Lu for treatment of HCC.

Transdermal patches: Design and current approaches to painless drug delivery

Use of transdermal patches can evade many issues associated with oral drug delivery, such as first-pass hepatic metabolism, enzymatic digestion attack, drug hydrolysis and degradation in acidic media, drug fluctuations, and gastrointestinal irritation. This article reviews various transdermal patches available in the market, types, structural components, polymer role, and the required assessment tools. Although transdermal patches have medical applications for smoking cessation, pain relief, osteoporosis, contraception, motion sickness, angina pectoris, and cardiac disorders, advances in formulation development are ongoing to make transdermal patches capable of delivering more challenging drugs. Transdermal patches can be tailored and developed according to the physicochemical properties of active and inactive components, and applicability for long-term use. Therefore, a number of chemical approaches and physical techniques for transdermal patch development are under investigation.

Molecular Modeling of Complex Cross-Linked Networks of PEGDA Nanogels

Poly(ethylene glycol) (PEG)-based nanogels are attractive for biomedical applications due to their biocompatibility, versatile end group chemistry, and ability to sterically shield encapsulated drug molecules. The characteristics of a hydrogel network govern the encapsulation and efficient delivery of drug molecules for a target application. A molecular-level description of network topology can complement experimental investigations to understand its effects on the structural properties of these nanogels. In this work, atomistic molecular simulations of heterogeneous, nonideal PEG-diacrylate (PEGDA) nanogels are presented. The effects of cross-linking density and topological features on the structural properties of PEGDA nanogels were studied. The average functionality was controlled to systematically study the effect of cross-linking density on the radius of gyration, shape, and mesh size of the nanogels. For a given average functionality, the impact of distinct network topologies on the structural properties was also studied. The aspect ratios, based on the gyration tensor, were calculated to characterize the shapes of these nanogels for different topologies. Nanogel structures with higher cross-linking densities showed a globular shape, while structures with lower cross-linking density showed shape anisotropy. The distribution and connectivity of the cross-linked junctions played a key role in determining the size and shape anisotropy of PEGDA nanogels; the number of unreacted chain ends and their connectivity directly affected the anisotropy. The mesh size, denoted by the limiting "free volume element" present in the nanogel samples, does not show a significant change with increasing average functionality. This work provides insight into the structural properties of heterogeneous hydrogels that aid the design of nonideal nanogel networks for a targeted drug delivery application.

[Modeling and theoretical analysis of ring specific mimicry in view of isomerism within medicinal promising oligomers of "DIVEMA"]

The furan or pyran related hetero cycles play basic role in structural units of nucleic acids (NA) and polysaccharides (PS), significantly predetermining their functional specifics. Some of such properties, in great relevancy for medicine, can be imitated through mimicry of polymers synthetic. Particularly, a formation of similar cycloisomeric chains is possible in process of free-radical cyclocopolymerization of divinyl ether (DVE) and maleic anhydride (MA). The products yielded (DVEMA) of general formula [DVE(MA)-alt-MA]n become precursors for a broad family of water-soluble derivatives capable of wide spectrum of bioactivity, including induction of interferon, immune-stimulated and direct antiviral protection. In this connection, the knowledge: what is content of different heterocyclic isomers in backbone of the preparations and what their partial contributions in promotion of the certain bioactivities observed, are in great importance. Available experimental data (NMR, IR, etc.), controversial for interpretations, didn't elucidate a required estimation of the DVEMA isomerism. The current work represents an independent exploration of the problem via quantum chemistry-based analysis of kinetic (activation barriers) and thermodynamic (enthalpies) priorities in competition between variable isomerism within the chain synthesis. The system is considered in maximal range of hypothetically allowable variations of two levels for double regioselective bifurcations: there are four competitive ways, each of which involves a sequence of four type elementary reactions for a diverse-isomeric formation of chain units. A genesis of six chiral centers (62 stereoisomers permitted) per every of the four part ways was accounted in view for up to 256 isomeric variations in total. The required time-minimized but precisely accurate computations were conducted via B3LYP/6-31G(d), M06-2X/6-311+G(d), M06-2X/6-31+G(2df,p) techniques, which were preselected through model test-systems. As a result, the mechanisms, crucial points and factors for the process-permitted regulation of isomeric content of DVEMA were studied in details. The narrow enough set of most probable enantiomers within highly competitive 5-exo- and 6-endo- ring closing sub-ways was revealed. The results obtained are very actual for an adequate modeling (docking / molecular dynamics) of DVEMA derivatives in their interactions with biopolymer targets, in search for purposed advancement of current background in design and synthesis of highly effective agents for combined antiviral protection (against HIV, flu, herpes, and other infections).

Structured Polyvinyl Alcohol/Zeolite/Carbon Composites Prepared Using Supercritical Fluid Extraction Techniques as Adsorbent for Bioethanol Dehydration

Introduction. Adsorption is a purification process with a more efficient energy level than others. Adsorption performance is strongly influenced by the ability of the adsorbent to be used; therefore, the modification of the adsorbent becomes a very important key for the purification process that occurs. Methods. In this study, the preparation of composite adsorbents was carried out by combining polyvinyl alcohol (PVA), zeolite (Zeo), and activated carbon (AC) as precursors. The crosslinking process was fulfilled by adding glutaraldehyde to the precursor mixtures followed by a supercritical fluid CO2 extraction (SFE) technique to create conditions for the crosslinking process. The composites were analyzed using Braunner–Emmet–Teller (BET) surface area analysis, Fourier-transform infrared (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy with energy dispersive X-ray (SEM/EDX-mapping), while individual and composite adsorbents were evaluated for their ability in bioethanol dehydration at various initial concentrations of ethanol and temperature. Results. The BET characterization shows that composite preparation under supercritical CO2 conditions provides reasonable surface areas, which are proportional to the content of activated carbon. The crosslinking process has been described by FTIR data interpretation, showing that PVA and glutaraldehyde were properly distributed on Zeo and AC precursors. The DSC characterization results give information that PVA successfully forms hydrophilic composites within Zeo and AC. The SEM micrograph analysis shows the formation of pores on the surface and cross section in structured adsorbents. The experimental adsorption shows that an increasing amount of AC in the composites increases the capacity of water adsorption (i.e., 0.80 gram of water/gram of adsorbent for PVA/Zeo/AC = 1 : 1 : 1 at 22°C). However, the effect is not significant when the ratio of AC is less than 0.5. As expected, the lower temperature increases the adsorption capacity. Further, by using approximately 4.5 gram adsorbents composite in 30 ml of water-ethanol mixtures, high concentration of bioethanol (>99%) can be achieved at various temperatures from 22°C to 40°C and bioethanol initial concentration from 88% to 96%. Conclusion. The SFE technique provides distinguished adsorbents composite properties. Further, the new composites provide about four times better adsorption capacity than that showed in the individual adsorbents test. The addition of AC influences on increasing the capacity and adsorption kinetics value.

Understanding copolymerisation kinetics for the design of functional copolymers via free radical polymerisation

We report the free radical copolymerisation kinetics and co-monomer sequence distribution for a series of functional copolymers based on MMA.

Chitosan/Poly(vinylpyrrolidone) Matrices Obtained by Gamma-Irradiation for Skin Scaffolds: Characterization and Preliminary Cell Response Studies

Several studies have shown that chitosan possesses characteristics favorable for promoting dermal regeneration and accelerated wound healing. In this work we have reported the work that has been done on the development and characterization of biocompatible and biodegradable chitosan based matrices to be used as skin scaffolds. Poly(vinylpyrrrolidone) (PVP) was used as copolymer and a two steps methodology of freeze-drying and gamma irradiation was used to obtain the porous matrices. The influence of PVP content, synthesis procedure and absorbed radiation dose on matrices’ physical, chemical and structural properties was evaluated by ATR-FTIR, TGA, SEM, contact angle measurements and degradation behavior. The in vitro cellular viability and proliferation of HFFF2 fibroblast cell line was analyzed as a measure of matrices’ biocompatibility and ability to assist skin regeneration. Results show that over the studied range values, gamma-radiation dose, copolymer concentration and synthesis procedure can be used to tailor the matrices’ morphology in terms of porosity and surface roughness. Early results from biological assays evidence the biocompatibility of the prepared chitosan/PVP matrices since cells adhered to the surface of all matrices (chitosan/PVP (5%) γ-irradiated at 10 kGy presents the higher cellular viability). These features show that the resultant matrices could be a potential suitable scaffold for skin tissue regeneration.

Characteristics of Local Delivery Agents for Treating Peri-Implantitis on Dental Implant Surfaces: A Preclinical Study

Local delivery agents (LDAs) are widely used in peri-implantitis treatments. The aim of this study was to identify LDAs remaining on the dental implant surfaces and to analyze the components of these residues after applying various cleaning methods. Implants were prepared with a sand-blasted, large-grit, acid-etched surface. Four kinds of LDAs were applied on the implant surfaces: chlorhexidine gel (group 2), tetracycline solution (group 3), and 2 kinds of minocycline hydrochloride agents (groups 4 and 5). Group 1 received normal saline as a control. Two cleaning methods were applied for different durations as follows: (1) running distilled water for 10 seconds (subgroup A), 5 minutes (subgroup B), and 15 minutes (subgroup C); and (2) water spray of a dental-unit chair for 10 seconds (subgroup D) and 5 minutes (subgroup E). Scanning electron microscopy and energy-dispersive x-ray spectroscopy were used to analyze the surface morphology and residue components for all implants. The amount of LDA removed from the implant surfaces in groups 1, 2, 3, and 5 increased with the cleaning duration and pressure. However, Minocline remained coated on the implant surfaces in group 4 under all cleaning conditions. Minocline could not be cleaned off well by water due to its hydrophobicity. Therefore, directly using this agent on implant surfaces with peri-implantitis should be carefully considered. The presence of LDA residues without drug efficacies on implant surfaces might interfere with reosseointegration and act as a reservoir of microorganisms.

Phenanthroline-A Versatile Ligand for Advanced Functional Polymeric Materials

The controlled incorporation of phenanthroline moieties into polymers is introduced, demonstrating their application as metal-ion complexing ligands for the construction of advanced macromolecular structures. Specifically, two phenanthroline-containing monomers based on acrylate and styrene functionalities, were synthesized. Each monomer was readily copolymerized with either N,N-dimethylacrylamide or styrene via nitroxide-mediated polymerization, resulting in narrowly distributed polar or non-polar copolymers. To demonstrate the versatility of the established polymer systems, the polar polymer was employed for transition metal induced single-chain nanoparticle formation, verified by diffusion-ordered NMR and UV/Vis spectroscopy. Furthermore, the non-polar polymer allows facile incorporation of lanthanide ions, creating luminescent metallo-polymers, in-depth characterized by advanced photophysical experiments and 2D NMR measurements.

Superior anti-neoplastic activities of triacontanol-PEG conjugate: synthesis, characterization and biological evaluations

Triacontanol (TA, C30H62O), abundantly present in plant cuticle waxes and bee waxes, has been found to display promising anti-neoplastic potentials. As a long chain fatty alcohol, TA possesses limited aqueous solubility, which hinders its medicinal application. To overcome its solubility barrier, a polymer prodrug was synthesized through attaching TA to poly ethylene glycol (PEG), using succinic acid as a linker with bifunctional amide and ester bonds. Anti-neoplastic effects of PEG-TA were assessed in LoVo and MCF7 cells, anti-proliferative and apoptosis-inducing activities were subsequently confirmed in mouse xenograft model. Encouragingly, PEG-TA possessed selective anti-cancer ability. It did not exhibit significant cytotoxicity on normal cells. Mechanistic examination revealed inhibition of NF-κB nuclear translocation, suppression on matrix degradation enzyme and down-regulation of angiogenic signaling might contribute to its anti-malignant effects. Pharmacokinetics clearly indicated PEGylated TA (named as mPEG2K-SA-TA) substantially enhanced TA delivery with increased plasma exposure (19,791 vs. 336.25 ng·mL-1·h-1, p < .001), mean residence time (8.46 vs. 2.95 h, p < .001) and elimination half-life (7.78 vs. 2.57 h, p < .001) compared to those of original TA. Moreover, mPEG2K-SA-TA appeared to be safe in preliminary toxicological assessment. PEGylated TA also emerged as a functional carrier to deliver hydrophobic chemotherapeutic agents, since it readily self-assembled to micelles in aqueous solution with a low critical micelle concentration (CMC, 19.1 µg·mL-1). Conclusively, PEG-TA conjugate displayed superior anti-neoplastic activities and low toxicity, as well as facilitated the delivery of other hydrophobic agents, which appeared to be an innovative strategy for cancer therapy.

Miscibility of poly(acrylic acid)/poly(methyl vinyl ketone) blend and in vitro application as drug carrier system

A series of poly(acrylic acid)/poly(methyl vinyl ketone) (PAA/PMVK) blends with different compositions were prepared by the solvent casting method. The miscibility of this pair of polymers was investigated by differential scanning calorimetry(DSC), Fourier transform infra-red (FTIR) and X-Ray diffraction (XRD) techniques. An in-vitro cytotoxicity test of the drug-carrier system via MTT (3-(4,5-demethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay revealed no significant cytotoxic effects at concentrations up to 100 µg· ml⁻¹. The STX/PAA-50 drug carrier systems were also prepared by solvent casting of solutions containing the sulfamethoxazole (STX) used as drug model and PAA/PMVK blend in N.N-dimethylformamide then crosslinked with acidified ethylene glycol. The release dynamic of STX from the prepared hydrogels was investigated in which the diffusion through the polymer matrix, the enhancement of the water solubility of STX, the influence of the initial drug concentration, the pH of the medium, and the effect of the degree of swelling of the polymer matrix on the release dynamic was evaluated. According to the total gastrointestinal transit time estimated by Belzer, the estimate distribution of STX released in the different organs indicated that the performance is obtained with the drug – carrier-system containing equal ratios of polymer and 10 wt% of STX (STX-10/PAA-50).

Native-mimicking in vitro microenvironment: an elusive and seductive future for tumor modeling and tissue engineering

Human connective tissues are complex physiological microenvironments favorable for optimal survival, function, growth, proliferation, differentiation, migration, and death of tissue cells. Mimicking native tissue microenvironment using various three-dimensional (3D) tissue culture systems in vitro has been explored for decades, with great advances being achieved recently at material, design and application levels. These achievements are based on improved understandings about the functionalities of various tissue cells, the biocompatibility and biodegradability of scaffolding materials, the biologically functional factors within native tissues, and the pathophysiological conditions of native tissue microenvironments. Here we discuss these continuously evolving physical aspects of tissue microenvironment important for human disease modeling, with a focus on tumors, as well as for tissue repair and regeneration. The combined information about human tissue spaces reflects the necessities of considerations when configuring spatial microenvironments in vitro with native fidelity to culture cells and regenerate tissues that are beyond the formats of 2D and 3D cultures. It is important to associate tissue-specific cells with specific tissues and microenvironments therein for a better understanding of human biology and disease conditions and for the development of novel approaches to treat human diseases.

Stimuli Responsive Polymeric Systems for Cancer Therapy

Nanoscale polymers systems have dominated the revolution of drug delivery advancement. Their potential in the fight against cancer is unrivalled with other technologies. Their functionality increase, targeting ability and stimuli responsive nature have led to a major boom in research focus. This review article concentrates on the use of these smart polymers in cancer therapy. Nanotechnologies have shown potential as drug carriers leading to increased drug efficacy and penetration. Multifunctional smart carriers which can release their payload upon an external or internal trigger such as pH or temperature are proving to be major frontrunners in the development of effective strategies to overcome this disease with minimal patient side effects.

Effects of Dendrimer-Like Biopolymers on Physical Stability of Amorphous Solid Dispersions and Drug Permeability Across Caco-2 Cell Monolayers

The potential applications of dendrimer-like biopolymers (DLB) as stabilizing excipients for amorphous solid dispersion (ASD) of niclosamide, celecoxib, and resveratrol were evaluated based on (1) the formation and physical stability of the ASD and (2) the permeability and flux of the agents across Caco-2 cell monolayers. The evaluation was made by comparing the performance of prototype phytoglycogen derivatives (DLB1, DLB2, and DLB3) with commonly used polymers such as HPMCAS, PVPVA, and Soluplus®. PXRD was used to confirm the formation of the dispersions and detect crystallinity peaks formed during 2- and 4-week storage at 40°C/75% RH. At concentrations below 2 g/mL, the viability of Caco-2 cells remained above 80% for all DLB samples compared to untreated cells in the MTT assay. Permeability studies revealed a repeating pattern in which an increase in the initial concentration (C₀) was associated with a concomitant decrease in the apparent permeability (P_app) which we theorize is due to differences in drug-polymer interactions. Niclosamide-DLB1 dispersion had the lowest flux due to a significant reduction in P_app. The high increase in the C₀ of celecoxib-DLB2, however, made up for the reduction in the P_app and produced the highest flux values compared to other polymers. Resveratrol-DLB3 had a 5× reduction in P_app, but C₀ increased from 25.8 to 176 μg/mL led to a higher flux compared to the crystalline drug without polymer. Collectively, these results provide a "proof-of-concept" basis to demonstrate that DLB excipients have the ability to increase apparent solubility (Sol_app), most likely due to drug-binding capacity.